In message <51881140.5070904@xxxxxxxxx>, Brian E Carpenter writes: > On 07/05/2013 02:10, l.wood@xxxxxxxxxxxx wrote: > > http://labs.apnic.net/blabs/?p=309 > > > > an excellent detective story on badly-written, poorly edited, standards track RFCs leading to interop pro > blems. Enjoy. > > I don't that is quite right. The problem in this case is not to do > with linguistic quality. It's due to a lack of formal verification > among a set of interacting and cross-area RFCs. (And the problem > is wider, because there are two distinct places in IETF standards > where ABNF for the text representation of IPv6 addresses can be > found.) This is a case where no amount of language editing would > have helped. Actually I used it a couple of months ago in a > discussion with some experts on formal verification, and they rather > liked it as a poster child for the need for formal methods in SDOs. > > Brian Apples mail client is broken [IPv6:2001:df9::4015:1430:8367:2073:5d0] is not legal according to both RFC 5321 and RFC 2821 which is all that applies here. RFC 2821 was consistent with RFC 2373 and the SMTP literal spec has remained frozen since then which you want when you are trying to promote long term interoperability. Now one could update RFC 5321 to accept the above :: instead of a single :0: but you could never legally send it. Note for IPv4 [070.0.0.0] is 70.0.0.0 not 56.0.0.0 despite the fact that many system will take 070.0.0.0 and send to 56.0.0.0. Mark -- Mark Andrews, ISC 1 Seymour St., Dundas Valley, NSW 2117, Australia PHONE: +61 2 9871 4742 INTERNET: marka@xxxxxxx